SpaceDog SpaceDog - 9 days ago 6
iOS Question

Correct ISO value for AVFoundation camera

While working with

AVFoundation
I use these two properties to know the minimum and the maximum
ISO
a device camera can use:

AVCaptureDeviceFormat *activeFormat = _videoDevice.activeFormat;
minISO = activeFormat.minISO;
maxISO = activeFormat.maxISO;


But these lines give me the following results back:

minISO = 23
maxISO = 736


But there is no such thing as
ISO
23 or 736. In fact, if you adjust the camera with
ISO
23 it will adjust itself for
ISO
50 and
ISO
736 will make the camera adjust to
ISO
800.

Is there a way to know the real
ISO
s a given camera can use before setting it up?

Answer

It's based on the film speed. The most common ISO values start at 25, and the following values are doubles (e. g. 50, 100, 200, 400). Wikipedia: Film Speed lists all values.